Download Practicing Protein Synthesis

Practicing Protein Synthesis
Name: ____________________________________
Date: ____________________________ Per: ____
1. What amino acids do the following mRNA sequences code for?
GGC
UACACG
CAG
UAUACG
UAG
UAGACG
2. What amino acids do the following DNA sequences code for?
TAC
AAT
TCA
GGCTAC
3. What sequence of mRNA could code for the following amino acids?
Cysteine
Tyrosine
Stop
4. What sequence of DNA could code for the following amino acids?
Arginine
Tryptophan
Stop
How DNA Controls the Workings of the Cell
Below are two partial sequences of DNA bases. Sequence 1 is from a human and sequence 2 is from a cow. In
both humans and cows, the sequence contains the gene to make the protein insulin. Insulin is necessary for the
uptake of sugar from the blood. Without insulin, a person (or a cow) cannot digest sugars the same way others
can, and they have a disease called diabetes.
Using the DNA sequence, make a complimentary mRNA strand from both the human and the cow. Write the
mRNA directly below the DNA strand (remember to substitute U's for T's in RNA). Use a codon chart to
determine what amino acids are assembled to make the insulin protein in both the cow and the human. Write
your amino acid chain directly below the RNA sequence.
Table 1: Human Sequence
DNA
mRNA
Amino
Acid
CCA
TAG
CAC
GTT
ACA
ACG
TGA
AGG
TAA
CGA
AGG
CAC
Table 2: Cow Sequence
DNA
mRNA
Amino
Acid
CCG
TAG
CAT
GTT
ACA
ACG
Analysis: Answer the following questions using complete sentences
1. Comparing the human gene to the cow gene, how many of the codons are exactly the same?
2. How many of the amino acids in the sequence are exactly the same?
3. Could two humans (or two cows) have some differences in their DNA sequences for insulin, yet still make
the exact same insulin proteins? Explain.
4. Find ALL of the codons that can code for the amino acid leucine and list them. There are 6.
5. Diabetes is a disease characterized by the inability to break down sugars. Often a person with diabetes has a
defective DNA sequence that codes for the making of the insulin protein. Suppose a person has a mutation in their
DNA and the first triplet for the insulin gene reads T A T. The normal gene reads T A G. What amino acid does the
mutant DNA and the normal DNA code for and will the person with this mutation be diabetic?
Another mutation changes the insulin gene to read T C T (instead of the normal T A G). Will this person be
diabetic? Explain.
6. DNA sequences are often used to determine relationships between organisms. DNA sequences that code for a
particular gene can vary, though organisms that are closely related will have very similar sequences. This table
shows the amino acid sequences of 4 organisms. Based on these sequences, which two organisms are most
closely related? Explain.
Human:
CCA TAG CAC CTA
Chimpanzee:
CCA TAA CAC CTA
Pig:
CCA TGT AAA CGA
Cricket:
CCT AAA GGG ACG
7. An unknown organism is found in the forest and the gene is sequenced as follows:
Unknown: CCA TGG AAT CGA
What kind of an animal do you think this is given the four choices in the table above? Explain why you made
that choice.